If a CALL statement includes one or more alternate return
specifiers among its arguments, control may be transferred to one of the
statement labels indicated, depending on the action specified by the
subroutine in the RETURN statement.

The argument list built-in functions %VAL and %REF
are supplied to aid interlanguage calls by allowing arguments to be passed by
value and by reference, respectively. They can only be specified in
non-Fortran procedure references.